1. Field of the Invention
The present invention relates to an organic light emitting diode device and a method of manufacturing the organic light emitting diode device, and more particularly, to an organic light emitting diode device that can be manufactured using a wet process and a method of manufacturing the organic light emitting diode device.
2. Description of the Related Art
An organic light emitting diode device includes an anode, a cathode, and an organic light emitting layer disposed between the anode and the cathode. In the organic light emitting diode device, electrons and holes are supplied from the cathode and the anode to the organic light emitting layer and are recombined with each other. Then, light is emitted from the organic light emitting layer as the energy level of the electrons is changed from an unstable state (an excited state) to a stable state. An organic light emitting diode display device using such an organic light emitting diode device does not require a backlight unit that is required for a liquid crystal display device. Thus, the organic light emitting diode display device can be light and slim. Furthermore, the organic light emitting diode display device can be manufactured through a simple process at lower costs. In addition, advantages of the organic light emitting diode display device include low-voltage operation, high light emitting efficiency, and wide viewing angle. For this reason, the organic light emitting diode display device is considered to be the next generation of a display device.
The organic light emitting diode device can further include a hole injection layer and a hole transport layer that are interposed between the anode and the organic light emitting layer. In this case, holes can be supplied from the anode to the organic light emitting layer through the hole injection layer and the hole transport layer, thereby increasing the light emitting efficiency and lifespan of the organic light emitting diode device.
A method of manufacturing such an organic light emitting diode device includes sequentially forming a hole injection layer, a hole transport layer, and an organic light emitting layer on an anode.
The hole injection layer, the hole transport layer, and the organic light emitting layer can be formed using a vacuum deposition process or a wet process according to materials of the hole injection layer, the hole transport layer, and the organic light emitting layer. For example, a vacuum deposition can be used for a low polymer, and a wet process can be used for a high polymer.
A wet process does not require expensive equipment and can be used for a larger substrate as compared with a vacuum deposition process. Furthermore, the wet process is suitable for mass production since the wet process is simple as compared with the vacuum deposition process.
However, when the wet process is repeatedly used for forming a plurality of organic layers, one organic layer can be dissolved or swelled by a solvent used for forming another organic layer. For example, after forming a hole transport layer using a first solvent, an organic light emitting layer can be formed on the hole transport layer using a second solvent. In this case, the hole transport layer can be dissolved or swelled by the second solvent. Moreover, the organic light emitting layer can be dissolved or swelled by the first solvent remaining on the hole transport layer. For this reason, the first solvent should be highly volatile and have no affect on the organic light emitting layer, and the second solvent should not dissolve the hole transport layer although it dissolves the organic light emitting layer.
Furthermore, when a hole injection layer is formed under the hole transport layer, it is more difficult to select solvents for the respective layers.
For this reason, when an organic light emitting diode device is manufactured using a wet process, it is difficult to form both the hole injection layer and the hole transport layer. Therefore, although the organic light emitting layer is formed in the organic light emitting diode device, both the hole injection layer and the hole transport layer cannot be formed in the organic light emitting diode device (that is, only one of the hole injection layer and the hole transport layer is formed). Moreover, it is also difficult to select materials for the hole injection layer and the hole transport layer.
Therefore, when an organic light emitting diode device is manufactured using a wet process, the light emitting efficiency and lifespan of the organic light emitting diode device can be decreased although manufacturing efficiency is high.